Network Working Group R. Fielding Request for Comments: 2616 ...

SHOULD include an entity containing a list of resourcecharacteristics and location(s) from which the user or user agent canchoose the one most appropriate. The entity format is specified bythe media type given in the Content-Type header field. The originserver MUST create the resource before returning the 201 status code.If the action cannot be carried out immediately, the server SHOULDrespond with 202 (Accepted) response instead.A 201 response MAY contain an ETag response header field indicatingthe current value of the entity tag for the requested variant justcreated, see section 14.19.10.2.3 202 AcceptedThe request has been accepted for processing, but the processing hasnot been completed. The request might or might not eventually beacted upon, as it might be disallowed when processing actually takesplace. There is no facility for re-sending a status code from anasynchronous operation such as this.The 202 response is intentionally non-committal. Its purpose is toallow a server to accept a request for some other process (perhaps abatch-oriented process that is only run once per day) withoutrequiring that the user agent's connection to the server persistuntil the process is completed. The entity returned with thisresponse SHOULD include an indication of the request's current statusand either a pointer to a status monitor or some estimate of when theuser can expect the request to be fulfilled.10.2.4 203 Non-Authoritative InformationThe returned metainformation in the entity-header is not thedefinitive set as available from the origin server, but is gatheredfrom a local or a third-party copy. The set presented MAY be a subsetor superset of the original version. For example, including localannotation information about the resource might result in a supersetof the metainformation known by the origin server. Use of thisresponse code is not required and is only appropriate when theresponse would otherwise be 200 (OK).Fielding, et al. Standards Track [Page 59]RFC 2616 HTTP/1.1 June 199910.2.5 204 No ContentThe server has fulfilled the request but does not need to return anentity-body, and might want to return updated metainformation. The